Ruth Davidson writes in The Mail on Sunday

ONE thing we have learnt to our cost over the last few years is that a failure to bear down on our debts comes at a heavy and often brutal price.

Governments all around the world have woken up to the fact that the money tree really doesn’t exist.

For many nations close to home, the hangover has been painful and harsh. For us too.

Having witnessed this, the majority of Scots last year saw the SNP’s independence plan for what it was when it was presented as a cost-free all-expenses-paid option which would somehow sweep the natural laws of economics aside.

Most people figured that if it looks too good to be true, then it probably isn’t.

But the fact is that as we prepare for a General Election in less than two months time, the SNP’s fantasy economics are back.

The same tactic of ignoring the economic reality, promising the earth, and angrily sweeping aside anyone who questions faith-based arithmetic is back.

And there is a real danger that, this time round, not just Scotland but all of Britain could sleepwalk over the precipice.

Put simply, the SNP wants to take control of Britain’s credit card and use it to create havoc with our carefully won reputation for financial solvency.

Not content with trying to break up the country, it now appears their plan is to form an alliance with Labour so they can bankrupt it too.

The plan will start immediately if, as they now openly boast, the SNP makes massive gains at the election on May 7th.

This, they hope, will give them the balance of power at Westminster. The second part of the plan then kicks in as they aim to prop up a weak Ed Miliband Labour government, and then demand it dances to their tune.

Leave aside for the moment that this would include weakening our defences by ending our nuclear deterrent at Faslane.

The central demand outlined by Nicola Sturgeon is that Mr Miliband must open the money taps and borrow an extra £180 billion.

You suspect this will not be too hard an ask given the left wing instincts of red Ed.

Ms Sturgeon dresses up this plan as a ‘modest increase’ in spending which the country can easily afford. I’m afraid that’s just disingenuous.

The reality is that, just as we had got to the point of getting our finances under control, her plans would mean Labour and the SNP opening up the cheque book once again to pile yet more debts onto our children and grandchildren.

How much would this cost? Treasury analysis – which has been unchallenged by the SNP – found this week that by the end of this decade, the Sturgeon plan would add extra debt interest of £5 billion.

That’s £5 billion every year going to foreign lenders, rather than to schools and hospitals. This she calls social justice.

That, however, is just stage one. Stage two comes if the SNP gets its way to impose independence by the back door.

Ms Sturgeon has confirmed this week that separation remains her goal, and has refused to rule out another referendum soon.

But, in the meantime, the goal is to settled for what the Nationalists call “full fiscal autonomy”.

Under this plan, we’d remain in Britain, but all the financial ties we currently share with the rest of the UK would be severed.

And Scotland’s system of public services would rest entirely on the shoulders of the poor, benighted Scottish taxpayer.

The full implications of this plan were exposed last week.

Figures produced by the Scottish Government’s own civil servants found that last year we received £800 more per head from the UK than we paid in.

That imbalance will shoot higher next year because the tumbling oil price means Scotland is paying in less and less in tax. And yet it remains the SNP’s plan to force us to rely on this anyway.

What would this mean? The impartial Institute of Fiscal Studies concluded that if the SNP wanted to fill the hole on its finances with tax rises, it would have to increase your income tax rates by 15p.

It wouldn’t do so of course. You guessed it, instead it would borrow, borrow and then borrow some more. It’s the kind of economic strategy that would make a Greek finance minister blush.

It’s no wonder, given this kind of attitude to spending, to learn that John Swinney is preparing to use new limited borrowing powers that come in next month to the max.

He is perfectly entitled to do so, and he may have his reasons.

But it gives us a clear idea of how the SNP would act if it got hold of all Scotland’s economic levers.

None of this should come as a surprise, of course. The SNP’s stated aim is to end the United Kingdom so it has little need to concern itself with the UK’s economic health.

No, the surprise is that Labour won’t tell them where to get off. Ed Miliband still refuses to rule out a deal with the SNP. He knows he may need to deal with the SNP after the election of he is to keep his job, and get into Number Ten.

Disgracefully, Mr Miliband is putting our nation’s hard won reputation at risk because he cares more about his political career.

We need to think about the long-term – a need which was illustrated perfectly just last week.

Chancellor George Osborne announced that Britain had finally paid back the debts it incurred from the war. The First World War.

More than 100 years after the original ‘war bonds’ were issue, the money owed to investors is finally to be paid back in full.

If nothing else, it was a timely and salutary reminder of just how long our debts take to clear – and how it is future generations which have to pick up the cost.

The fact is that I don’t want our grandchildren and great-grandchildren to still be weighed down by massive debts in 100 years time. I don’t believe it’s fair.

I believe it’s only fair that we try to keep that burden as low as we can.

It was once said of socialists that they always end up running out of other people’s money.

But in the case of the SNP, they won’t even accept that there is a moment when we can’t keep spending.

We need a responsible government which will keep our economic recovery on track – and one which gets us back in the black so our national debt starts falling.

What we can’t afford – and future generations can’t afford – is a Labour-SNP pact which would only add debts upon debt, leaving us all worse off.